fix: validate responsive real-content targets

src/components/AppShell.vue

@@ -34,6 +34,7 @@ const canonicalNavigation = computed(() => canonicalSectionIds.map((id) => ({ id
   <header class="site-header">
     <h1>{{ content.identity.name }}</h1>
     <p>{{ content.identity.role }}</p>
+    <p class="print-portfolio-label" aria-hidden="true">Portfolio</p>
     <SiteNavigation :items="canonicalNavigation" />
   </header>